1. Field of Invention
The present invention relates to a manufacture method for a structure of semiconductor device. More particularly, the present invention relates to a manufacture method for a pixel structure of a thin-film transistor (TFT) liquid crystal display (LCD).
2. Description of Related Art
As a fact of rapid improvement in the multi-media society, it mainly is due to the benefits of great development on the semiconductor devices or the displaying device. With respect to the displaying device, the TFT-LCD with great properties of high image quality, high efficiency of space use, low power consumption and radiation has gradually become a main trend in the market.
The TFT-LCD is mainly composed of a TFT-array substrate, a color-filter-array substrate, and liquid crystal layer, wherein the TFT-array includes multiple TFT's arranged in an array manner, and pixel electrodes respectively implemented with TFT, so as to form multiple pixel structures. According to the foregoing TFT, the TFT includes a gate electrode, a channel layer, source/drain electrodes to serve as a switching device for the liquid crystal displaying unit.
FIGS. 1A–1E are cross-sectional views, schematically illustrating the conventional manufacture process flow for a pixel structure. In FIG. 1A, a gate electrode 110 is formed on a substrate 100. Then, a gate insulating layer 120 is formed on a substrate 100, and covers over the gate electrode 110. A semiconductor layer 130 is formed on the gate insulating layer 120. The semiconductor layer 130 includes a channel material layer 132 and an ohm contact material layer 134. Then, a metal layer 140 is formed on the semiconductor layer 130. Also and, a photoresist layer 150a is formed on the metal layer 140.
In FIG. 1B, the photoresist layer 150a is used as the etching mask to pattern the metal layer 140 (see FIG. 1A) to form a source electrode 142/drain electrode 144. In addition, the ohm contact material layer 134 (see FIG. 1A) is patterned to form an ohm contact layer 134a. 
In FIG. 1C, the photoresist layer 150a (see FIG. 1B) is removed, and another photoresist layer 150b is formed on the source electrode 142/drain electrode 144. The photoresist layer 150b further covers the region between the source electrode 142/drain electrode 144. Here, since the photomask, used to form the photoresist layer 150b, is the photomask used in a conventional 5-step manufacture process, the photoresist layer 150b being defined has the channel island or channel peninsula pattern without fully covering the drain electrode 144.
After then, the photoresist layer 150b and the source electrode 142/drain electrode 144 thereunder are used as the etching mask to pattern the channel material layer 132 (see FIG. 1B) for forming a channel layer 132a. Wherein, since the photoresist layer 150b does not cover the drain electrode 144, a portion of the drain region 144 without being covered by the photoresist layer 150b is also bombard by the plasma during the etching process.
In FIG. 1D, the photoresist layer 150b (see FIG. 1C) is removed and a passivation layer 160 is formed over the substrate 100. In addition, an opening 162 is formed in the passivation layer 160 to expose the drain electrode 144.
In FIG. 1E, a pixel electrode 170 is formed on the passivation layer 160, and the pixel electrode 170 is electrically coupled to drain electrode 144 through the opening 162 (see FIG. 1D).
In the foregoing descriptions about the conventional method, the photoresist layer 150b does not fully cover the drain electrode 144. In this manner, when the channel material layer 132 is patterned, a portion of the drain electrode 144 is also bombarded by the plasma, causing an increase of contact impedance between the pixel electrode 170 and the drain electrode 144 at the portion being bombarded by the plasma. This may also cause the poor performance for the TFT displaying device.